Disappointing turbo performance

[toyotaracer9]

I dont think you need to be precise but the best chance you have at getting it to spool is to making the turbo manifold and charge pipe shorter.

Yea it sounds like yours would be hard to take off in a church parking lot without completely smoking the tire down. The manual may be more fun but I doubt its more efficient with these underpowered bikes, when you shift you go from lets say 10hp down to 5hp then build back up to 10hp. A CVT keeps you up at 10hp until you reach desired speed. That turbo is too big for your engine, so the only place you may get lucky is way up top.

[gearhead1951]

You COULD remove the turbine part and replace it with a pulley to make it an engine driven supercharger !

Solves most of the problems you are experiencing !

[toyotaracer9]

You COULD remove the turbine part and replace it with a pulley to make it an engine driven supercharger !

Solves most of the problems you are experiencing !

A turbo spins at over 100000rpm, it would be a fan . If you wanted to belt drive a smog pump would be better option

[gearhead1951]

friend of mine back in TN did that trick with big rigs turbo on a 300" 6 cylinder ford , 8 t0 1 overdrive (16" engine pulley to 2" driven pulley) !

Got 15 lbs of boost at 7000 engine rpm (till the engine grenaded on him)

[Banzaibob]

Since the turbo is spooling up AND giving me 7-9psi of boost AND apparently over-fueling (thick black smoke most of the time) isn't it fair to say that the turbo is simply too restrictive to the exhaust? What about this; what would be wrong with brazing a fitting that would accept a 1" quarter turn stainless or brass ball valve in the pipe between exhaust port and turbo? I could take it out on my test road and simply "dial in" a bypass setting that would give me less restriction and still spool up the turbo. All of the parts ARE working and I've evidently got boost to spare. The only component that appears suspect is exhaust restriction. Discuss?

[toyotaracer9]

The turbo is too big, not too small. Just because you have boost pressure doesnt mean its spinning fast enough to get out of lag. The engine cant even make the WG open, most engines could make 25-35lbs of boost when the turbo is sized properly and you use the WG to keep the boost at your desired level.

[Banzaibob]

Too big.....My apologies, I'm simply not getting it. This engine is exhibiting every indication that the turbo is restricting the exhaust flow. I have even ran the engine with the turbo hooked up on the exhaust side and disconnected on the intake side and it actually behaves the same, anemic power, sooty black smoke, etc. I must admit being a babe in the woods when it comes to making a turbocharged diesel run right but you must forgive me when I say that what you are telling me appears counter-intuitive.

[BertTrack]

I'll try putting things in perspective a bit.

I've got a 75bhp diesel car engine (in my car) with turbo. And i think the turbo is about simular/smaller than yours. Whenever i want to get that max power from it it easily pushes the pressure to double that of the atmosphere (not comfortable with psi).

No matter what the size is. To get the higher pressures you need the turbo to run high rpm. There is no other way. So you need to put in the power on the exhaust side.

Even if you inject enough fuel to power the motorcycle and drive the turbo you're not getting enough air when you accelerate to begin with. Most turbo systems will open the fuel pump more as the psi of the turbo increases. Keeping your manual max amount from sooting up @ low rpm. You may have to simulate that effect.

Make sure the engine is hot/warm. Then rev it in lower gear with low load to create max exhaust/air flow. Then add load and see if it picks up turbo pressure enough.

But besides that, To create the psi's in the inlet you need the energy in the exhaust, and the fuel to be burned (and injected) Which could be a problem aswell.

Also having the black smoke means you're cooling your exhaust with the excess of fuel. Try to find the sweet point with less throttle. My old Golf TD had that aswell. (if it turns to white/grey smoke the fire just went out)


So:

Rev up (low gear) and shift up while trying to stay in the upper rev band. If that works better your turbo is too big for the engine with lower revs.

Sorry for the jumbled post i'm in the night shift atm.

But! I think your turbo is too big. And it thus acts as a restrictor. I think the turbo on my Track is tiny. But it's the right side for 45hp. (could be too big)

[Banzaibob]

We're talking about the IHI RHB31. I believe it is also referred to as VZ21. This is advertized as "the world's smallest turbo." The compressor output is 25mm in diameter. Turbine input, about the same. Are you telling me that that the one in your car is smaller? If there is dimensionally a smaller one, I have not seen it. Tell me where I can find one smaller than this one. (It is a little bigger than my fist.)

[BertTrack]

I've done some searching online, Found that those turbo's are intended to be used on the Japanese 660cc engines in the small car class over there. They have aprox 47kW standard. Based on that, your engine is too small

http://www.vespalabs.org/User:Internets ... bo_Charger interesting specs here.

[toyotaracer9]

I'll try putting things in perspective a bit.

I've got a 75bhp diesel car engine (in my car) with turbo. And i think the turbo is about simular/smaller than yours. Whenever i want to get that max power from it it easily pushes the pressure to double that of the atmosphere (not comfortable with psi

1bar. = 14.7psi


Bansai, just because you have the worlds smallest turbo(which its not) doesnt mean it will work for your application. A good place to go from here is to read some online info about turbos to get an understanding, especially how the turbine wheel is designed(shaped) blocks exhaust flow if not spooled fast enough. It seems like it has you confused.

[Banzaibob]

I have no problem admitting I'm am indeed confused. On the one hand I've got 7 to 9 psi of boost at the top end of the rpm range (I could probably get even more). It is therefore safe to say (in my confused mind) that the compressor is indeed doing its job. With my admittedly limited knowledge I know that the turbine is spinning around in there enough to create the type of pressure that I had hoped to get. But.......it runs like it has got a potato in the tail pipe. To back that seat of the pants assertion up, it is puking out thick, black, oily smoke, surely a by product of incomplete combustion.

It would seem to me (again with my dubious novice charm) that since there is nothing wrong with the flow and/or pressure on the intake side that the incomplete combustion could perhaps be caused by the incomplete evacuation of the spent fuel charge vis a vis, exhaust restriction. Discuss?

[BertTrack]

Well without changing anything the one thing you can try it babysit it up in power keeping it just outside of the blacksoot area. If the turbo has a benefit to offer in your current setup it should do that outside of the soot area.

Once you start making soot you're giving the turbo less power to work with. Which could explain the potatoe in the tail pipe feeling.

Does it feel like it has more power when not running full throttle? (My old Golf did just before it started to soot)

[Banzaibob]

Yes, I've tried the "babysitting" thing by lightening the throttle once it stops accelerating. The black smoke subsides. In the lower gears, 2nd and 3rd it pulls to the top of it's revs and it runs much smoother on top , albeit slower than without the turbo. I have a fuel stop that keeps me from over fueling. I backed in out so I would get more fuel, more fuel makes it run worse.

So, I need a smaller turbo? Wouldn't a "dimensionally" smaller turbine/exhaust aperture be more restrictive? ...OR is it the notion that since the exhaust pressure is not great enough to spin said turbine up to speed, that is why my exhaust stream is more restricted. (?) If that were true, then why is it giving me a healthy boost on the intake side of 9psi?

[Nanko]

Maybe your pressure gauge is not fast enough to see the pressure drop when the intake valve opens.
It easy goes below atmospheric pressure , resulting in less air entering the combustion chamber.

[Banzaibob]

I was under the impression that that was why a 1300cc plenum was used in the intake stream.

[Nanko]

Ignore my reply, ofcourse the pressure never gan go below atmospheric if the plenum volume is larger than de engine displacement

[Banzaibob]

Rather than let this thread or especially this project go dark, I've decided to come up with some solutions that if it doesn't improve performance, at least it will give me positive information as to which way to go. I would greatly appreciate all of your thoughts.

I have decided to take things incrementally. First, I need to find out what the exhaust pressure is and if there is a huge differential between boost. I've included a picture of a valve that I have welded into the header pipe. Obviously this is for test purposes, if it works I'll use a more elegant solution. I haven't tapped the header for a nipple to check the pressure yet but that is next. One thing I hope to do with the valve is as I am doing my road test I will gradually open the valve. Any improvement in performance should give me an answer. Consequently, no improvement or a dramatic decrease in boost should give me an answer also.

[BertTrack]

I just thought of the muffler. Have you tried running without it? (probably have)

[Banzaibob]

The addition of a manual exhaust relief valve yielded no increase in performance. Pretty much what happens when you open it is that boost drops. Normal, relaxed throttle settings (30-40mph in 3rd or 4th gears) produce in between 2 to 4psi of boost. Full throttle and maxing out the rpm until the governor kicks in varies depending on road conditions between 6 and 10psi of boost.

The bike's entire performance envelope appears to have changed. When it was normally aspirated and the injection timing was retarded it pulled well from the lower rpm range but lacked serious strength on top. Now it appears that it the opposite and is a very "peaky" engine. So much so that it almost seems as if I was to gear it down so it will rev high in 5th gear I might be able to reach my target of 70mph. I base this on the notion that at 50mph in 5th gear it could very well simply NOT be on it's power band. Revving it out in 4th gear can get me up to 50mph with about 6psi of boost and then shifting into 5th is like opening a parachute. It starts to sit and dog until it can only pull 45mph with maybe 2psi of boost at best.

So......let me me ask all of you a series of questions: These Yanmar 10 horse engines are designed to run at 3600rpm all day, day in day out. Since it looks like my only hope of seeing power gains through turbocharging is going to come at high rpm's, 1) Anybody have a good means of installing a rev counter/tachometer on these things? And 2) what is a safe red line? 3) Anybody ever tried beefier lower end bearings or tighter valve springs to keep it from exploding?

[alexanderfoti]

There are other people who have used this turbo on the 400cc yanclones and have had some increases fromthis model turbo, so I don't think that's the issue here...

[BertTrack]

Is there a way to bolt the turbo to the exhaust port? That way you get more usable energy even at lower revs.

You really do seem to have a lack of energy left in mid rpm's at the turbo to give it some boost. And then it'll work like a restrictor. (your parachute effect)

Oh you could try on a downhill stretch to see it will reach that 70mph in fifth and then as it levels off see it can then sustain it at those higher rpm's

[alexanderfoti]

The addition of a manual exhaust relief valve yielded no increase in performance. Pretty much what happens when you open it is that boost drops. Normal, relaxed throttle settings (30-40mph in 3rd or 4th gears) produce in between 2 to 4psi of boost. Full throttle and maxing out the rpm until the governor kicks in varies depending on road conditions between 6 and 10psi of boost.

The bike's entire performance envelope appears to have changed. When it was normally aspirated and the injection timing was retarded it pulled well from the lower rpm range but lacked serious strength on top. Now it appears that it the opposite and is a very "peaky" engine. So much so that it almost seems as if I was to gear it down so it will rev high in 5th gear I might be able to reach my target of 70mph. I base this on the notion that at 50mph in 5th gear it could very well simply NOT be on it's power band. Revving it out in 4th gear can get me up to 50mph with about 6psi of boost and then shifting into 5th is like opening a parachute. It starts to sit and dog until it can only pull 45mph with maybe 2psi of boost at best.

So......let me me ask all of you a series of questions: These Yanmar 10 horse engines are designed to run at 3600rpm all day, day in day out. Since it looks like my only hope of seeing power gains through turbocharging is going to come at high rpm's, 1) Anybody have a good means of installing a rev counter/tachometer on these things? And 2) what is a safe red line? 3) Anybody ever tried beefier lower end bearings or tighter valve springs to keep it from exploding?

I have installed a tachometer using a hall effect sensor and a boat tacho that redlines at 4000 rpm.

I belive they are safe up until around 3800rpm, then you need stiffer valve springs.

[Banzaibob]

As an earlier poster stated, a lot of people who use these Yan-clones also use a CVT. They can simply run it full throttle until it gets happy. With a manual transmission it has to be happy from the git-go.

I have looked at bolting it as close to the exhaust port as possible and using significantly smaller diameter pipe. I would have side clearance to mount it directly to the port but a proper mount would be difficult. The exhaust header I have on there now has a volume of approximately 33 cu.in. I am going to move the entire turbo closer and work toward having a header volume of under 10 cu. in.

I am getting the impression that entire game rests on whether or not I can get the turbo to give more boost at lower rpm's. I have an SOHC Honda 750 that is punched out to 836cc that I can see great things happening with one of these turbos, but..... The bottom line? The Honda (or any other normal bike for that matter) has zero charm and esoteric value compared to having a usable, functional and roadworthy diesel bike.

[alexanderfoti]

As an earlier poster stated, a lot of people who use these Yan-clones also use a CVT. They can simply run it full throttle until it gets happy. With a manual transmission it has to be happy from the git-go.

I have looked at bolting it as close to the exhaust port as possible and using significantly smaller diameter pipe. I would have side clearance to mount it directly to the port but a proper mount would be difficult. The exhaust header I have on there now has a volume of approximately 33 cu.in. I am going to move the entire turbo closer and work toward having a header volume of under 10 cu. in.

I am getting the impression that entire game rests on whether or not I can get the turbo to give more boost at lower rpm's. I have an SOHC Honda 750 that is punched out to 836cc that I can see great things happening with one of these turbos, but..... The bottom line? The Honda (or any other normal bike for that matter) has zero charm and esoteric value compared to having a usable, functional and roadworthy diesel bike.

You need to calculate volumetric efficinecy and flow per stroke etc to gauge whether it would drive the turbo. I ran these calculations when I was planning on fitting a supercharger (to calculate the drive speed for the supercharger)

mazdog had good results with the RBH31 with a manual gearboxed l100 - https://www.dieselbikeforum.com/view ... f=32&t=903

[Banzaibob]

I read the Mazdog posts. Didn't he fry his turbo after 100 miles?

As an aside; I have several Goldwings laying around waiting for restoration/parting out. I found out tonight a friend is willing to donate his Mercedes-Benz 110 cu. in. diesel motor. The Goldwing clutch/trans is driven by a hy-vol chain inside the the clutch case. Shouldn't be a problem exposing via sawsall. Discuss?

[alexanderfoti]

I read the Mazdog posts. Didn't he fry his turbo after 100 miles?

As an aside; I have several Goldwings laying around waiting for restoration/parting out. I found out tonight a friend is willing to donate his Mercedes-Benz 110 cu. in. diesel motor. The Goldwing clutch/trans is driven by a hy-vol chain inside the the clutch case. Shouldn't be a problem exposing via sawsall. Discuss?

Yeah, but only becuase he had a restriction in the oil supply which starved the journal bearings

Maybe send him a PM, to see what his performance etc was like?

Best to start a new thread for the mecedes/goldwing conversion, does the gearbox share the same oil supply in the goldwing?

[Banzaibob]

I believe I will send him a PM.

I had another idea, please tell me if you think I am on the right track. One of the possible problems I see is air restriction at low rpm levels. The intake apertures are around 25mm or so. When the turbo is not spooled up at idle or just above idle during a normal takeoff I would think that the entire turbo circuitry would impede airflow. I have a reed cage/valve from a Yamaha YZ250 2 stoke. I was thinking about mounting it to the plenum. At idle and just above it would be sucking in air but as soon as the turbo spooled up the added pressure would close the valve. Any ideas on this?

Also, are there any java thingies that I can plug in my known numbers and come up with volumetric efficiency? Sorry, I'm lazy.

[pietenpol2002]

Hey Banzai, you might try contacting Boxerotto regarding his experience with the turbo'd Yanclone.

https://www.dieselbikeforum.com/view ... 9425#p6333

Or, perhaps you can get Heiko to comment on his experience. My link to Heiko in the above thread is dead. So, use the one below.

http://forum.dieselkrad.info/index.php? ... ko#msg_997

[Banzaibob]

Damn, I thought for a second there that I had an original idea (reed valve). Although he does not go into specific performance detail, it appears as if he is getting satisfactory performance out of it. I think that if I had one complaint about the machines that people build it would be that there's not a lot of follow up. Of course that may be because they are out enjoying the fruits of their labor or it could be that the thing blew up and the bike sits in the corner of the garage in low priority mode waiting for parts.

All last summer (before turbo) this bike was my "go to the store bike."